Groupon shares tumbled 20 percent to the lowest price in company history Monday after the daily deals website disappointed investors with its second quarter earnings results.

Groupon beat profit estimates, usually a good sign, but revenue was lower than expected, fueling already existing concerns about the company’s growth potential.

“We’re happy with the growth that we continue to see,” Groupon CEO Andrew Mason told investors in an earnings call. He called it a “solid quarter.”

Groupon reported $568 million in revenue, which was higher than the company’s $393 million in revenue during the same period last year, but it missed Wall Street estimates by about $5 million.

Analysts were expecting 46 percent growth in sales to $573.1 million.

Groupon also reported $46 million in income, which was slightly higher than the company’s earlier outlook, and earnings per share of 4 cents, which beat estimates by 1 cent.

It was an improvement from 2011. During the same period last year, Groupon reported a loss of $101 million or 35 cents per share.

Groupon also grew its customer base to 38 million users, up from 36.9 million last quarter and 23 million a year ago.

Groupon’s outlook for the third quarter includes an increase in revenue up to $580 million to $620 million, a decrease in income down to $15 million to $35 million, and stock-based compensation of $30 million. This compares with Wall Street’s expectation of 47 percent growth for the rest of the year.

But investors were hoping for more. Groupon shares rose from a low of $6.63 on Friday to open Monday at $7.94. The stock traded most of the day around $7.60, and closed at $7.55, but fell as low as $6.02, when the earnings results were released after the markets closed.

Groupon has fallen nearly 80 percent since it went public at $28 on Nov. 4, 2011. The previous low was $6.35.

Groupon’s last earnings report was a welcome surprise by many investors. In May, the company noticed a 27 percent rise the day after it was released, but it slowly trickled away.

This comes as investors are losing faith in a number of popular social media stocks and seem to have little patience for disappointing performances.

Facebook shares have fallen about 45 percent since the company went public on May 18. The company’s first earnings report on July 26 was a disaster, sending the stock price to a record low. It closed that day at $26.85, but tumbled in after-hours trading and opened the next day at $23.19. It is now trading at $21.60.

Zynga’s stock has also disappointed investors. It opened on Dec. 16, 2011, at $11, but is now trading at $2.93.

While Groupon is pleased with its growth in the U.S., at 66 percent year-over-year, Mr. Mason said Europe is “far under-penetrated.” But the companies problems go beyond the financial crisis over there. Groupon admitted it needs to do a better job of promoting relevant deals to Europeans through deal personalization.

“We believe we are not totally dependent on a macroeconomic turnaround in Europe to improve our performance there,” Mr. Mason said. “The mix of deals we feature can have a substance effect on our performance. We have found these more discretionary offers are more susceptible to negative growth.”